Bright nickel plating



United States Patent 051cc Fatented July 5, 3%55 BRIGHT NICKEL PLATING Otto Kai-dos, Thomas I. Menzel, and James L. Sweet,

Matawan, N. 5., assignors to Hanson-Van Winkle- Munning Company, a corporation of New Jersey No Drawing. Application March 24, 1953, Serial No. 344,481

7 Claims. (Cl. 204-49) This invention relates to bright nickel plating, and this application is a continuation in part of our copending application Serial No. 241,894, filed August 14, 1951 (now abandoned). The invention is based on the discovery that water-soluble acetylenic compounds, when incorporated as addition agents in a nickel electroplating bath in combination with various sulfo-oxygen compounds of the sulfonic acid type, are remarkably effective for promoting the formation of bright and ductile nickel electrodeposits from such bath. We have found that all water-soluble acetylenic compounds are effective brighteners when used in combination with a sulfa-oxygen compound; and we have found that in all instances the use of the sulfo-oxygen compound in combination with the acetylenic compound leads to improved results as compared with use of the acetylenic compound alone. Nonetheless it is possible to obtain commercially acceptable bright nickel deposits when using certain water-soluble acetylenic compounds alone as the brightening agents incorporated in the bath, and the invention therefore contemplates the use of such compounds alone.

A preferred process according to this invention for producing bright nickel deposits comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt, in which there is dissolved from about 0.02 to 3 grams per liter of a water-soluble acetylenic compound, together with about /4 to about 80 grams per liter of a water-soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sult'onamides and imides.

While any water-soluble acetylenic compound can be employed with success in the above-defined process for producing bright nickel deposits, we have had particular success, particularly as regards production of ductile bright electrodeposits, when using an acetylenic compound selected from the group consisting of Z-butyne- 1,4-diol, 4-methoxy-2-butyn-1-ol, diethylamino-2-butyn-l-ol, 4-(N-morpholinyl)-2-butyn-1- o1, 3-pentyn-l-ol, 2,4-heXadiyne-L6-diol, and l-diethylamino-Z-propyne. Compounds from among this group which have been found to be very satisfactory are those which have the formula in which R1 is a hydroxyl, hydroxymethyl or hydroxyethyl radical, R2 is a hydrogen or methyl radical, and R3 is selected from the group consisting of methyl, hydroxymethyl, hydroxyethyl, methoxymethyl, diethylaminomethyl, morpholinomethyl, and hydroxypropyne radicals. Compounds having this general formula, and other compounds in the group particularly specified above, are effective brighteners in nickel electroplating 3-hexyne-2,5-diol, 4-

baths and lead to the formation of bright nickel deposits of adequate ductility for many purposes, even when used alone (i. e. when no suite-oxygen compound is used in combination with them), when dissolved in the bath in an amount ranging from about 0.2 to about 3 grams per liter.

When any of these compounds is thus used alone as brighteners in the electroplating bath, the nickel deposit produced from such bath is brilliant, but at a thickness of about 0.001 inch (0.025 mm.), it is likely to be rather brittle, as indicated by slight cracking of the deposits and noise production when the article on which the deposit is formed is bent. When, however, the acetylenic compound is used in the electroplating bath in combination with a suite-oxygen compound of the character described, the concentration of the acetylenic compound can be very considerably reduced (e. g. to one-tenth to one-fifth of the concentration required to give a brilliant nickel deposit in the absence of the sulfa-oxygen compound) without loss of brilliancy, and in general with a substantial increase in ductility of the electrodeposit.

As described in our aforementioned copending application Serial No. 241,894, not all water-soluble acetylenic compounds are suitable when used alone as nickel brighteners in nickel electroplating baths. However, all watersoluble acetylenic compounds which we have been able to test yield smooth bright electrodeposits when used in conjunction with one or more of the sulfo-oxygen compounds, and it is evident from our work that all water-soluble acetylenic compounds can be used successfully in such combination. Thus, use of the sulfo-oxygen compound considerably extends the range of acetylenic compounds that can be employed with success.

Brightener additions according to this invention have of course been used successfully in the standard Watts nickel electroplating bath. However, these brightener additions are also efiective in all other acid nickel electroplating baths, and the invention thereforeis applicable to any nickel electrodepcsition operation from an aqueous acidic solution of one or more nickel salts.

Examples of acetylenic compounds which we have used successfully in embodiments of this invention are listed in Table 1 below under the heading Group A compounds; and similarly, examples of sulfa-oxygen compounds which have been employed successfully in accordance with the invention are listed below under the head: ing B compounds.

uroup TABLE I Group A compounds 3-ethyl-1-heptyn-3 -ol,

l-ethynylcyclohexanol, HCECC(OH)C5H1O l-diethylamino-Z-propyne, CECCH2N(C2H5)2 2-butyne-l,4-diol, HOCHzCzCCHzOH 4-methoxy-2-butyn- 1 -01, HO CHzCz CCHzOCHs 1,4-dimethoxy-2-butyne, CHaOCI-IzCaCCHzOCHs l5) 4-octyne-3,6-diol, 1

CH3CH2CH(OH) CECCH(OH) CHzCHs (16) 2,5 -dimethyl-3-hexyne-2,5 -diol,

3-heXyne-2,5-diol, CHaCl-I OH CE CCH OH) CH3 When Group A compounds were used alone in a nickel plating bath containing 330 grams per liter nickel sulfate, 45 grams per liter nickel chloride, 37.5 grams per liter boric acid at pH=3.5, 50 C., 40 amperesrper square foot and with agitation, the results were as follows:

Compounds 10, 11, 12, 14, 18, 19, 20, 21 gave smooth, brilliant electrodeposits, but deposits which at thicknesses above 0.0005" were somewhat brittle. Optimum concentrations required to produce brilliant nickel deposits were approximately:

0.6 gram per liter of 0.8 gram per liter of #11 1.5 grams per liter of #12 or #14 0.4 gram per liter of #18 or #19 or #20 0.2 gram per liter of #21 (brilliant smooth nickel deposits in the higher current density range; patterned streaky deposits in the lower current density range).

Compounds 2, 3, 4, 5, 6, 7, 8, 9, 13, 15 gave at concentrations of the same order as above (0.2-0.8 gram per liter) patterned, streaky, wavy, flaky deposits, and it was difiicult to obtain smooth bright deposits at still lower concentrations over a reasonably wide range of current densities. The disturbing influence of these addition agents on cathodic crystal growth is apparently too strong.

Compound 16 was ineffective at 3.5 grams per liter and compound 17 gave at 0.6 gram per liter a dull deposit with some black streaks in the low current density area.

Compound 1 (acetylene) gave bright and dull patches when bubbled (after purification by passage through water) over the test panel.

Compound 22 (acetylene dicarboxylic acid) was only moderately elfective as a brightener'.

All compounds (except compound 10) which gave smooth brilliant nickel deposits had the structure All compounds which had too strong a disturbing influence on cathodic crystal growth contained a HCEC group. Only if, besides this group, they contained also an amino group (compound 10) did they give smooth, brilliant deposits over a reasonably wide current density range.

The ineffective compounds 16 and 17 contain the following group:

liter of naphthalene trisulfonic acid sodium salt) in a bath containing 330 grams per liter nickel sulfate, 45 grams per liter nickel chloride, and 37.5 grams per liter boric acid, at a pal-1:35, 50 C., 40 amperes per square foot average current density, on bent cathodes, and with air agitation, the minimum concentrations of the Group A compounds required to produce brilliant electrodeposits are approximately as shown in Table II.

TABLE II Grams Per Milllmoles W uewooooooocwww 1 Deposit obtained at this concentration was not 01' the highest bril lrancy obtalnab 2 Brilliant and grey areas were formed on the bent cathode.

Nickel deposits (0.001 inch thick) obtained with the ammo compound l0, l8, l9 and also with compounds 16 and 17 were somewhat brittle. The brightening action I of compound 1 (acetylene) was difficult to control. Hov

ever, bubbling acetylene (which had been Washed with water in a gas washing flask) through a standard (Watts) nickel bath containing 2 grams per liter of naphthalene trisulfonic acid for three minutes before plating led to the formation of nickel deposits which were brilliant over considerable areas, though somewhat pitted and'brittle.

The compounds listed in Table Ill are examples of sulfo-oxygen compounds which, when used in combination with a water-soluble acetylenic (Group A) compound, promote formation of brilliant and adequately ductile nickel deposits. The concentration values set opposite each compound in Table III were found to give good results when that compound was used in combination with 0.1 gram per liter of butynediol in a bath containing 330 grams per liter nickel sulfate, grams per liter nickel chloride, and 37.5 grams per liter boric acid at a pH of 3.5, at C., and 40 amperes per square foot average current density, using bent cathodes and with air agitation.

TABLE 111 Group .8 compounds (1) Unsaturated aliphatic sulfouic acids, and alkali metal, ammonium,

magnesium, and nickel salts thereof:

Sodium vinyl sulionate, H2O= CHSOgNfl 2 and 4 g./l.

Sodium allyl sulfonate, H2O=OHOHzSO Na 2 and 4 g./l.

Mononuclear aromatic sulfonic acids, and alkalik metal, ammonium,

magnesium and nickel salts thereof:

Benzene monosulionic acid, C@H5SO3H 2 and 4 g./l. Sodium benzene monosultonatc, GsHsS O Na 2 and 4 g./l. Nickel benzene monosulfonate, (CEHGS 0021351 i 2 and 4 g./l.

Sodium para-toluene monosulfonate, CH CsHzSO3Na 2 and 4 g./l. Para-chlorohenzene sulfouic acid, ClCfiH-QSCaH 2 and 4 g./l. Sodium para-chlorobenzene snlfonate, ClO6H4S03Na. 2 and 4 g./l. Sodium para-bromobenzene sultonate, BICBHlSOsNZL 2 and 4 g./l.

1, 2 dichlorobenzene sultonic acid, ClzGsHgSOgH 2 and 4 g./l. 1, 2, or 2,5 dichlorobenzene sulionate sodium salt,

ClzCsHaSOaNa 2 and 4 g./l. Sodium phenylethylene sulfonate, CeH5CH= OHSOgNa. 1 all. Meta benzene disull'onic acid, 065480311)? 2 to 40 gjl. Sodium meta-benzene disulfonate, CGHASOQNaM, 2 to 40 g./l. Nickel meta-benzene disullonate, C5H4(SO )2NL 2 to 40 g./l. Ortho-sulfobenzolc acid mouoa-mmonium salt,

HOCOC6H4SO3NH4, "Um" ,..l. .r. W... 2 g./l. 1-amino-2,5-benzenc disulfonic acid, HZNC5H3( S 033)! 2 and 4 g./l. Ortho-am'mooenzene sulfuric acid, HgNCfiILSOiH. Z and 4 gJl.

(3) Mononuclear aromatic sulfinic acids, and alkali metal, ammonium,

magnesium and nickel salts thereof:

Sodium benzene sulfinate, OGH5SO2N3 0.4 g./l.

Sodium para-toluene sulfinate, OHaCfiHASOzNEI 0.4 g./l.

(4) Mononuclear aromatic sulfonamides and 'unides:

Benzene sulfonamide, CeHss OzNHz Para'toluene sulionamide, CHZCBHASOQNHZ. Ortho'benzoic sulfimide, CaH C ONHSOz) g. g. g.

Naphthalene trisulfonic acid trisodium salt,

Diphenyl ppadisulfonic acid,HSO3CeH4CaH4SO3H Up to saturation (less than 2 g./l.) 2-naphthol-3,6-disulfonic acid, HOC1 H (S 03H) 2. i 4 all. 2-naphthol-3,6-disulionic acid sodium salt,

HOO0H5(SO3Na)z 4 g./l.

l-naphthylamine acid,

and nickel salts thereof: Thiophene sulfonic acid, C4H3S-SO3H 1 g./l. Sodium thiophene sulfonate, ornasspsNa 1 g./l. z-( pyn'dyl) ethyl sulfonic acidflaflm CHzCHsSOsH 2 g./l.

The concentrations given in Table III above are those at which brilliant nickel deposits were obtained but do not necessarily indicate optimum or maximum concentrations. In all cases the free sulfonic acids and their alkali metal, ammonium, magnesium, and nickel salts are the full equivalents of each other for purposes of this invention.

The following Table IV shows the results obtained on a bent cathode in a standard Watts sulfate-chloride-boric acid nickel plating bath under varying operating conditions at a pH of 3.5 and with air agitation:

At low current density and/ or high temperature the concentration of the naphthalene trisulfonic acid (or other Group B compound) should be kept rather low in order to avoid milkiness of the deposit in the low current density areas, especially if the butynediol (or other Group A compound) concentration is very low (say only 0.1 g./l.). At 0.2 g./l. of butynediol, the concentration limits for naphthalene trisulfonate are extremely wide. In the same nickel sulfate-chloride-boric acid bath at a pH of 3.5, at 50 C., and at 40 amps. per sq. ft., in the presence of 0.15 g./l. 3-pentyn-l-ol, 8 to 12 g./l. of benzene sodium sulfonate gave slightly brighter nickel deposits than did 4 g./l.; and 4 to 12 g./l. of meta-benzene disodium sulfonate gave slightly brighter nickel deposits than did 2 g./l. beyond the optimum, but still satisfactory.

When a Group B compound is used alone (i. e. not in combination with an acetylenic compound), only dull or whitish semibright to almost bright nickel deposits are obtained. Only when used in combination with an acetg Heterocyclic sulionic acids and alkali metal, ammonium, magnesium With each of these sulfonates l6 g./l. was

ylenic (Group A) compound do the sulfo-oxygen (Group B) compounds produce really brilliant nickel deposits. Also a leveling (smoothing) action is produced only in presence of a Group A (acetylenic) compound. In the standard sulfate-chloride-boric acid bath at 50 C. and amperes per square foot, with air agitation, the roughness values (root mean square values in microinches) shown in Table V were obtained with a brush surface analyzer on roughened panels before and after plating 0.001 inch of nickel.

If maximum ductility of the nickel deposits is required the concentration of Group A compounds should be kept at the minimum required to produce the desired degree of brilliancy, which is approximately the value given in Table II. For rapid buildup of brightness of relatively thin deposits (0.0001 to 0.0005 inch) higher concentrations of Group A brighteners (up to e. g. 0.4 or even up to a maximum of 1.0 grams per liter) may be used with advantage.

As mentioned above, the concentration range or" Group B addition agents is rather wide. There is a certain minimum Group B compound concentration, depending on the concentration of the Group A compound, the bath composition, and operating conditions, below which maximum brilliancy is not obtained. Increase in the concentration of Group B compound beyond this minirnum frequently produces more ductile nickel deposits.

The bath composition itself has some influence on the brightening effect of the Group A and Group B addition agents. Standard Watts baths containing 330 grams per liter sulfate, grams per liter chloride, 37.5 grams per liter boric acid and operated at a pH of 3.5, C., and 40 amperes per square foot, with air agitation, in which 25% to 100% of the nickel was replaced by cobalt, showed rather increased sensitivity to butynediol, when this Group A compound was used alone, but almost no sensitivity to naphthalene trisulfonic acid when this Group B compound was used alone or in combination with butynediol. Baths high in chloride ion concentration behaved similarly. A bath containing 240 grams per liter of nickel chloride and 30 grams per liter of boric acid gave brilliant nickel deposits with only 0.4 gram per liter of butynediol. Neither sodium naphthalene trisulfonate (2 grams per liter) nor para-toluene sulfonarnide (2 grams per liter) showed very strong cooperative effects when added to such high-chloride bath containing 0.1 to 0.4 gram per liter butynediol; but in a bath containing 255 grams per liter of nickel sulfate, grams per liter of nickel chloride and 37.5 grams per liter boric acid, normal cooperation of 2 to 4 grams per liter of naphthalene trisulfonate and 0.1 gram per liter butynediol, to yield brilliant ductile nickel deposits, was observed.

Brilliant nickel electrodeposits were obtained, in accordance with the invention, from the baths listed in Table VI, which were operated at a pH of 3.5 and at 40 amperes per square foot, with air agitation. The baths of Table VI are merely examples of the ranges of bath compositions that have been used successfully, and do 4 not indicate any limit of bath composition which can be employed in accordance with the invention:

K, comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved TABLE VI Bath concentrations in grams per liter Bath 1 Bath 2 Bath 3 Bath 4 Bath 5 Bath 6 Bath 7 Nickel Sulfate, N iSO4.7H2O 240-330 330 240 Nickel chloride, YiOl fiHzO Nickel tormate, N i(OOCH)2.2H2O Nickel fluoborate, N i(BF-1)z Nickel sulfamate, Ni(OaSNH2)2 c Sodium chloride, No.01 Sodium bromide, NaBr Boric acid, H3BO3 2-Butyne-1,-4-diol 1,3,6-Naphthalene trisulfonate. Temp, C

When using a standard Watts bath containing 0.1 gram per liter of butynediol and 2.0 grams per liter of 1,3,6-naphthalene trisulfonate, operated at 50 C. and 40 amperes per square foot, the optimum pH value is in the range from 3.0 to 5.0. At a pH of 2.5 the butynediol concentration must be increased (say, to 0.2 to 0.3 gram per liter) in order to produce a deposit of full brightness.

in order to obtain pit-free nickel deposits, it is advantageous to employ strong air agitation of well-filtered solutions, or alternatively to use less strong agitation of a bath containing a suitable wetting agent, such as up to 0.25 gram per liter of sodium lauryl sulfate.

We claim:

1. A process for producing bright nickel deposits which comprises electrodeposit'ing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.2 to about 3 grams per liter of an acetylenic compound selected from the group consisting of 2-butyne-l,4-diol, 4-methoxy-2-butyn-l-ol, 3- hexyne-2,5-diol, 4-diethylamino-2-butyn-l-ol, 4-(N-n1orpholinyl)-2butyn-l-ol, 3pentyn-l-ol, 2,4-heXadiyne-L6- diol, and l-diethylamino-2-propyne.

2. A process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.2 to about 3 grams per liter of a acidic solution of at least one nickel salt and containing (31% as an addition agent from about 0.3 to about 1.5 grams per liter of 2-butyne-1,4-diol.

4-. A process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved trcrn about 0.02 to 1 gram per liter of a watersoluble acetylenic compound and from about /11 to about 30 grams per liter of a Water-soluble sulfo-oxygen compound of the group consisting of unsaturated aliphatic sulfonicacids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, alkali metal, ammonium, magnesium and nickel salts of said acids, and mononuclear aromatic sulfonamides and imides.

5. A process for producing bright nickel deposits which from about 0.02 to about 1 gram per liter of a Watersoluble acetylenic compound selected from the group consisting of acetylene, Z-propyn-l-ol, 3-butyn-l-ol, Z-methyl- 3-butyn-2-oi, l-pentyn-S-ol, 3-rnethyl-l-pentyn-3-ol, 3,5- dimethyl-1-heXyn-3-ol, 3-ethyl-l-heptyn-3-ol, l-ethynylcyclohexanol, l-diethylamino 2'- propyne, 2-butyne-1,4- diol, 4-methoxy-2-butyn-l-ol, 1,4-dimethoxy 2 butyne, 3-hexyne 2,5 diol, 4-octyne 3,6 diol, 2,5-dimethyl-3- hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, 4-diethyl amino 2 butyn-lol, 4 (N-morpholinyl)-2-butyn-l-ol, 3-pentyn-l-ol, 2,4-bexadiyne-L6-diol, and acetylene dicarboxylic acid together with about .1 to about 40 grams fonamide, ortho-benzoic sulfimide, benzyl sulfonam'ide;

benzene sulthydroxarnic acid, N,N dimethyl para-toluene sulfonaniide, N,N dicarboxyethyl benzene sulfonamide, Z-naphthalene monosulfonic acid, 1,5-naphthalene disulfonic acid, 2,7-naphthalene disulfonic acid, 1,5-naphthalene disulfonic acid nickel salt, 2,7-naphthalene disulfonic acid nickel salt, naphthalene trisulfonic acid, naphthalene trisulfonic acid trisodium salt, diphenyl pp disuifonic acid, 2-naphthol-3,6-disulfonic acid, Z-naphthol- 3,6-disulfonic acid sodium salt, l-naphthylamine 3,6,8- trisulfonic acid, thiophene sulfonic acid, sodium thiophene sulfonatc, and 2-(4-pyridyl) ethyl sulfonic acid.

6. A process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 1 gram per liter of 2-butynel,4-diol and from about 1 to about 40 grams per liter of a water-soluble aromatic sulfonic acid.

"7. A process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 1 gram per liter of 2-butync-l,4-diol and from about 1 to about 40 grams per liter of a water-soluble salt selected from the group consisting of alkali metal, ammonium, magnesium and nickel salts of an aromatic sulfonic acid.

Belgium Dec. 15, 1950' 

1. A PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT IN WHICH THERE IS DISSOLVED FROM ABOUT 0.2 TO ABOUT 3 GRAMS PER LITER OF AN ACETYLENIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF 2-BUTYNE-1,4-DIOL, 4-METHOXY-2-BUTYN-1-OL, 3HEXYNE-2,5-DIOL, 4-DIETHYLAMINO-2-BUTYN-1-OL, 4-(N-MORPHOLINYL)-2-BUTYN-1-OL, 3-PENTYN-1-OL, 2,4-HEXANDIYNE-1,6DIOL, AND 1-DIETHYLAMINO-2-PROPYNE. 